1. Field of the Invention
The invention relates to a valve device that is used for a gas tank, which, in particular, is a gas tank that stores high-pressure gas.
2. Description of the Related Art
In general, a gas tank that stores high-pressure gas is provided with a valve device that interrupts the flow of the gas in a passage, through which the inside of the gas tank and the outside thereof communicate with each other. See Japanese Patent Application Publication No. 9-210296 (JP-A-9-210296), for example.
With regard to a gas tank for hydrogen gas mounted on a fuel cell vehicle or the like, development to achieve higher pressure resistance is in progress to increase the storage capacity. The storage pressure of hydrogen gas becomes higher and higher from 30 MPa to 50 MPa and to 70 MPa. Thus, it is desired that the gas tank be highly reliable so that gas leakage does not occur even under high-pressure conditions and have a highly accurate pressure regulation performance. In a passage for filling hydrogen gas into a gas tank, a check valve for preventing the stored hydrogen gas from flowing backward is provided in addition to a manual valve. For example, in order to secure the reliability, a valve device, in which multiple check valves are used, has been proposed.
In the valve device described in Japanese Patent Application Publication No. 2006-144841 (JP-A-2006-144841), a housing recess portion that opens at an outer side of a plug housing is formed and a manual valve is screwed into the housing recess portion. A plurality of check valves are arranged between the manual valve and the housing recess portion to reduce the size. In such a valve device, in which the check valve(s) are disposed in the plug, it is desirable that the check valve be disposed in the filling port side of the gas filling passage in order to facilitate the installation of the check valve(s) into the plug.
However, in the vicinity of the filling port of the filling passage, a filter for preventing dust etc. from entering the inside of the gas tank when hydrogen gas is being filled is provided. Thus, in order to dispose the check valve and the filter in the filling port side of the filling passage, a large space is required.